The overall objective of this research project is to provide information which will lead to improved restorative materials. This will be accomplished by establishing those specific physical properties which relate to and are predictors of clinical performance. The general approach is to characterize materials using laboratory physical property tests and to place these characterized materials clinically. The clinical performance is then related to the various physical property tests to determine which tests are most significant in this regard. Amalgam, pure gold and composite resins will be studied in this manner.